Studies show that women with hypothyroidism can often experience elevated levels of the hormone prolactin.
When the brain senses there isn’t enough thyroid hormone in the body, it stimulates a feedback system whereby the brain tells the thyroid to release more hormones.
Thyroid releasing hormone (TRH) stimulates the release the of thyroid stimulating hormone (TSH) to increase levels of T4 (thyroxine). At the same time as stimulating the thyroid hormone to release more hormones, TRH can also simultaneously gently stimulate lactotroph cells in the brain (these cells also release prolactin; ultimately this leads to an increase in release of prolactin (which might manifest as lactating even when you’re not breast-feeding or pregnant!)
Higher prolactin can mean your skin breaks out (prolactin can stimulate sebaceous gland activity), it can interfere with normal pulsing of GrRH which means you might get irregular menstrual bleeds, oh, it can also kill your libido!
High prolactin secondary to hypothyroidism can be reversed once the body has enough thyroid hormones, as well as when other factors (such as poor stress adaption; stress increases prolactin) are managed.